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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 27 Aug 2019 06:37:18 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x7R5bH8j48955528 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 27 Aug 2019 05:37:17 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2D6814C046; Tue, 27 Aug 2019 05:37:17 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CF0AF4C04A; Tue, 27 Aug 2019 05:37:16 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 27 Aug 2019 05:37:16 +0000 (GMT) Received: from adsilva.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id A2235A0300; Tue, 27 Aug 2019 15:37:15 +1000 (AEST) From: "Alastair D'Silva" To: alastair@d-silva.org Cc: Andrew Morton , Oscar Salvador , Michal Hocko , Mike Rapoport , Dan Williams , Wei Yang , David Hildenbrand , Qian Cai , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] mm: don't hide potentially null memmap pointer in sparse_remove_section Date: Tue, 27 Aug 2019 15:36:55 +1000 X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190827053656.32191-1-alastair@au1.ibm.com> References: <20190827053656.32191-1-alastair@au1.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 19082705-0016-0000-0000-000002A35CF4 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19082705-0017-0000-0000-00003303A5D6 Message-Id: <20190827053656.32191-3-alastair@au1.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-26_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=835 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908270062 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Alastair D'Silva By adding offset to memmap before passing it in to clear_hwpoisoned_pages= , we hide a theoretically null memmap from the null check inside clear_hwpoisoned_pages. This patch passes the offset to clear_hwpoisoned_pages instead, allowing memmap to successfully perform it's null check. Signed-off-by: Alastair D'Silva --- mm/sparse.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index e41917a7e844..3ff84e627e58 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -882,7 +882,7 @@ int __meminit sparse_add_section(int nid, unsigned lo= ng start_pfn, } =20 #ifdef CONFIG_MEMORY_FAILURE -static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages) +static void clear_hwpoisoned_pages(struct page *memmap, int start, int c= ount) { int i; =20 @@ -898,7 +898,7 @@ static void clear_hwpoisoned_pages(struct page *memma= p, int nr_pages) if (atomic_long_read(&num_poisoned_pages) =3D=3D 0) return; =20 - for (i =3D 0; i < nr_pages; i++) { + for (i =3D start; i < start + count; i++) { if (PageHWPoison(&memmap[i])) { num_poisoned_pages_dec(); ClearPageHWPoison(&memmap[i]); @@ -906,7 +906,8 @@ static void clear_hwpoisoned_pages(struct page *memma= p, int nr_pages) } } #else -static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pa= ges) +static inline void clear_hwpoisoned_pages(struct page *memmap, int start= , + int count) { } #endif @@ -915,7 +916,7 @@ void sparse_remove_section(struct mem_section *ms, un= signed long pfn, unsigned long nr_pages, unsigned long map_offset, struct vmem_altmap *altmap) { - clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset, + clear_hwpoisoned_pages(pfn_to_page(pfn), map_offset, nr_pages - map_offset); section_deactivate(pfn, nr_pages, altmap); } --=20 2.21.0